Hydrogen passivation is an important step in the fabrication of optoelectronic devices. Passivation isolates components on a semiconductor substrate by electronically and/or photonically deactivating doped regions. Hydrogen has been identified as a passivating species for n- and p- type III-V semiconductor materials. The substrate is exposed to hydrogen plasma, which diffuses through the doped film. The hydrogen reacts with dopant atoms to form neutral complexes, thereby passivating the region. The purpose of this work is to create a predictive computer simulation using a physically-based theoretical model and to validate the simulation against experimental data. The model involves both the reaction and diffusion of passivating species with dopant atoms, subject to charge-induced field effects. Experiments in undoped and Zn-doped material have been performed, and simulation results derived using proprietary software have shown excellent agreement between experiment and theory. As this software platform is no longer available, present work has focused on creating a stable numerical simulation using MATLAB. The theoretical model has been implemented for p-type material using a finite difference scheme, employing an iterative method for solving the time-evolution of the species in the passivated region. Initial results from MATLAB show consistency with the previous experimental and simulation data. Work continues to focus on increasing the robustness of the simulation to handle more physically-complex scenarios, including heterostructures and both n-type and mixed n/p-type substrates.